Introduction

The amsmath package provides a number of additional displayed equation structures   beyond the basic equation and eqnarray environments provided in basic /. The augmented set includes:

  equation    align
  gather      flalign
  multline    alignat
  split

Except for split, each environment has both starred and unstarred forms, where the unstarred forms have automatic numbering using /'s equation counter. You can suppress the number on any particular line by putting notag before the
; you can also override  it with a tag of your own using tag||\| or |ii| used to ``number'' the equation. There is also a tag* command that causes the text you supply to be typeset literally, without adding parentheses around it. tag and tag* can also be used within the unnumbered versions of all the amsmath alignment structures. Some examples of the use of tag may be found in the / sample files testmath.tex and subeqn.tex.

   
Table: Comparison of displayed equation environments (vertical lines indicating nominal margins)